difference between simple present and present continuous tense?

I found the "advanced grammar in use" in chapter 1, it said,"We can use the present continuous or the present simple to describe something that we regularly do at a particular time. " So that we can both tense to describe the repeated action.

In the exercise, some of them only can use simple present and some of then only can use present continuous tense. But can you tell me the difference of them?

Thank you